The present invention relates to a safety device for moving the cabin of a lift or elevator in case of a fault of the main lifting system.
More particularly, the invention concerns an auxiliary safety device for a lift system, adapted to displace upwardly a car or cabin stopped between two floors, to the level of the right above floor for allowing the passengers disembarkation.
As it is known when a sudden fault occurs in the main lifting system of a lift, the cabin can stay blocked between two floors at a level not allowing for the evacuation of the passengers.
Under the above circumstances it becomes necessary to move the cabin either upwardly or downwardly so as to return the cabin to a level corresponding to the nearest floor exit.
Italian patent No. 1 240 805 discloses a method for moving the cabin of a lift or hoist that has accidentally stopped between two floors.
In the system disclosed by patent No. 1 240 805 the cabin is housed within a cage having a height at least equal to the height of the cabin inclusive of its outer service members and augmented by the distance between the levels of two consecutive floor exits.
This cage is securely attached to the main lifting system but the cabin can be displaced upwardly or downwardly inside the cage through an auxiliary lifting device.
In case the cabin remains trapped between two floors, the cabin is caused to slidably move inside the cage, by the safety device, until it reaches a floor exit.
The cabin movement inside the cage is stopped when the cabin reaches the level of a floor exit, and then the lift door is opened to allow the passengers to evacuate the cabin.
A first drawback of the method disclosed by Italian patent No. 1 240 805 derives from the size of the cage in which the cabin is housed.
Namely, due to the cage presence the lift shaft need to be larger than usual, both in the lateral size and height.
For this reason the method disclosed by the above Italian patent cannot be employed in an already existing lift system, unless the cabin size is rendered so small that a properly dimensioned cage can be fitted inside the existing shaft.